一种最小应力的无源无损软开关方案

A Novel Lossless Passive Soft-switching Cell With Minimum Stresses

无源软开关技术控制和实现简单,工程应用广泛。文中提出一种适用于基本PWM DC/DC变换器的最小电压、电流应力无源无损软开关单元。实现开关管零电流开通、零电压关断,二极管软开关。开关管电压应力没有增大,增加的谐振电感有效抑制其电流峰值。同时,无源软开关单元钳位了二极管电压。在不增大原功率电路半导体器件的电压、电流应力条件下,实现软开关。文中以buck变换器为例,详细分析所提无源软开关方案的工作原理,给出无源网络参数设计过程,通过计算机仿真,并设计一台100 k Hz,200 V/5 A的buck样机。与硬开关进行效率对比,在20%到额定负载范围内,软开关方案的效率均优于硬开关。

Lossless passive soft-switching technologies are widely used because of their simplicity in control and implementation. A novel lossless passive soft-switching cell is proposed with minimum voltage and current stresses, which is suitable for all basic PWM DC/DC converters. The power switch turns on with zero current, and off with nearly zero voltage. Meanwhile, the diode switches on and off with soft. The voltage stress of the switch is not increased compared with the hard-switching counterparts, and its peak current is limited by an additional inductor. What＇s more, the voltage stress of the diode is limited with the help of clamping diodes. Soft switching is realized without increase of voltage and current stresses. The buck converter was taken as an example, the principles of the novel passive soft-switching cell were analyzed in detail and the procedure of passive parameters design was deduced. All analysis was verified by simulation and on a 100 k Hz, 200 V/5 A buck prototype. Compared with the hard switching, efficiency was tested from 20% to rated load, the proposed soft-switching scheme had a distinct better performance.